ST. LOUIS — David Ortiz, chairman of the impromptu gathering, didn’t clear it with his manager. In fact, he didn’t even consider such a thing. Protocol? What do you mean, protocol?

After all, it was the middle of Game 4 of the World Series, and the chance of another Red Sox title was slipping away faster than any radar gun could clock it. All Ortiz knew was that it was his time to talk.

“David doesn’t script much,’’ said Sox manager John Farrell, who watched with a blend of delight and admiration as Ortiz rallied the troops Sunday night at Busch Stadium. “And that certainly wasn’t scripted.’’

If the Sox go on to win their third world title in 10 seasons, Ortiz’s dugout speech, his Fall Classic carpe diem, likely will stand as the Series’ seminal moment.

Having fallen behind, two games to one, the Sox were at the precipice of dropping two back in the best-of-seven series, their bats again turned flaccid by stout Cardinals pitching.

Enough of that, said Ortiz. The sole holdover from Boston’s curse-busting
team in 2004, he summoned his teammates, some of whom looked frustrated and forlorn, to one end of the dugout. It was time for them to wake up, shake the clouds of doubt, and sense the opportunity.

This was the World Series, the big man reminded them, and though not everyone wins when they get to October, there are scores of players, some among the game’s greats, who never even get the chance to attempt victory.

“Like I told my teammates, ‘If you think you are [always] going to come to the World Series, you’re wrong, especially playing in the AL East,’ ’’ he said late Sunday night, his poignant words having helped the Sox rally to a 4-2 win. “Do you know how many people we beat up to get to this level? To this stage? A lot of good teams, a lot of good teams, man, and that doesn’t happen every year.

“I told them, ‘It took me [six] years to get back up to this stage, and we had better teams than what we have right now and we never made it. So take advantage of being here.’ ’’

Such was the crux of the Ortiz message. Sense the moment, seize it, before the dream of slipping on a diamond ring turns into a lasting choker of regret.

“I just saw a lot of faces, you know, looking in the wrong direction,’’ he said. “And every team has that guy [to speak up] and I think I am that guy here.’’

Thus, in that instant, he became not David Ortiz the designated hitter but Big Papi, prophet of horsehide-and-pine-tar resurrection. He talked. They listened. And they got it going, ignited by Ortiz’s leadoff double in the fifth inning that was only the second hit off St. Louis starter Lance Lynn. The other hit was Ortiz’s infield single in the second. Through four innings, his teammates stood an ossified 0 for 11.

“His words were spot-on,’’ said Farrell, who soon saw Ortiz wheel home with the run that tied the game, 1-1, on a Stephen Drew sacrifice fly. “I walked down close by and heard what he said. I can’t say everything that he said, but the message was spot-on. Whether it led to the inning that unfolded, he was right by what he said.

“It was more along the lines of, ‘We’ve gotten to this point because of the players we are.’ And I think what he was reflecting on is what we all sensed and felt, in that we weren’t having normal or typical at-bats.

“It just felt like there was maybe an overarching mood that needed to be jolted and snapped out of, and that’s what took place.’’

If the Sox win one more game, Ortiz will be the hands-down World Series MVP. After going 3 for 3 in Sunday night’s emotional win, he logged in with another 3 for 4 (two singles and an RBI double) in Monday’s Game 5. He will bring an unfathomable .733 batting average into Game 6 Wednesday night at Fenway.

But neither baseball-reference.com nor the Elias Sports Bureau keeps track of verbal grand slams such as the one Ortiz delivered in Game 4. In the inning after Ortiz’s double helped bring the Sox even, Jonny Gomes submitted the kill shot, smacking a three-run homer over wall in left for a 4-1 lead. The invisible tail on that comet had Ortiz’s wisdom written all over it.

“Any time this guy steps in the box,’’ said Gomes, “there’s a presence. Any time this guy puts a uniform on, there’s a presence. If this guy wants to rally us together for a pep talk, it was like 24 kindergartners looking up at their teacher.

“He got everyone’s attention and looked him right in the eyes. That message was pretty powerful.’’

All in all, said Gomes, the speech was the “little kick in the butt that we needed.’’

Next month Ortiz will turn 38, old in baseball years, and he will be some 20 years removed from first signing a pro contract with Seattle as a 17-year-old from the Dominican Republic.

“I was just a baby,’’ Ortiz mused late Sunday night, noting to a media member from Arizona that he started his pro career in the minor leagues as a naive teen in Peoria, Ariz. “And that was a real 17 — none of that ‘Dominican 17.’ ’’

Those 20 summers factored into what Ortiz had to tell his teammates Sunday night in a dugout grown sullen. His experience spoke with nearly the same thump as his maple bat.

Asked to reflect on his undaunted, infectious October enthusiasm and a batting average that reads like a Boeing jetliner’s model number, Ortiz said, “How should I be? I don’t have another 10 years in me. I don’t know when I’m going to be back in the World Series. So, got to give everything I have right now.’’

Infielder Xander Bogaerts just turned 21 years old. He is the youngest of the Red Sox in this World Series. The day he was born, Ortiz was that wide-eyed teen-ager in the Dominican Republic, dreaming of the life baseball might bring him.

Now Bogaerts has a locker next to Big Papi, and Sunday night he was all ears and wonderment when Ortiz said what he had to say.

“I never had no one do that in the minors, and we’re in a World Series, so he did it at a good time and he got us going,’’ said Bogaerts.

“Whenever he talks, everyone listens. He’s respectful to all of us and we give him the same respect he deserves. It was a pretty amazing moment.’’